Various devices have been used to submerge metal scrap in molten metal. A scrap submerging device can be used in a melting system for converting scrap metal into metal ingots. Molten metal contained in a hearth is circulated by a pump contained in a pump well. In one design, molten metal is drawn from the hearth by the pump and circulated from the pump well to a scrap charging well, to a dross well and back to the hearth. Scrap metal such as aluminum can scrap is added to molten metal in the charge well. It is important to facilitate rapid melting of the scrap, but this is difficult to do because the scrap has a low density causing it to float.
Some devices have mechanical equipment located above a charge well that physically submerges the scrap in the molten metal. Other devices utilize an impeller in the scrap charging vessel to pull the scrap into the molten metal. Yet other devices utilize a pump located outside of the charge well that pumps molten metal into a vessel contained by the charge well without the need for mechanical equipment in the charge well itself.
U.S. Pat. No. 3,272,619 discloses an apparatus for adding solids to liquid, which includes a pump positioned next to a vortexer vessel. A riser of the pump extends outside the molten metal and pumps molten metal onto the surface of the molten metal at a top of the vortex vessel. This is believed to cause undesirable oxidation in view of the exposure of the molten metal to the atmosphere. The U.S. Pat. No. 3,272,619 patent also discloses an apparatus that pumps molten metal into a bottom of the vortex vessel. However, this device employs a riser extending from a base of the pump outside the molten metal, may lead to build up or freezing of molten metal in the riser.
U.S. Pat. No. 6,217,823 discloses using a ramp to achieve a vortex with an initially upward flow of molten metal adjacent outer walls inside the scrap charging vessel and then downwardly toward an outlet of the vessel. The U.S. Pat. No. 6,217,823 patent contrasts its invention from a downward flow scrap submergence apparatus disclosed in U.S. Pat. No. 4,286,985. The apparatus of the U.S. Pat. No. 4,286,985 patent includes an upper well inlet and a bottom well outlet positioned to create a downward flow of molten metal adjacent the side wall of the well to form the vortex. Moreover, the device described in the U.S. Pat. No. 4,286,985 patent disclosure requires two interconnected inlet passages into the scrap charging well, one at the surface of the molten metal and one beneath the level of the molten metal. The device of the U.S. Pat. No. 4,286,985 patent disclosure operates based on suction or negative pressure. The device of the U.S. Pat. No. 4,286,985 patent disclosure uses a specially shaped pump well into which an impeller on the end of a shaft is rotated in a chamber. The U.S. Pat. No. 4,286,985 patent discloses that an inlet, the first surface passage, the second, below-surface passage, the pump well and the charge well are formed in the same block of material, which prevents separate cleaning and repair of the pump well and charge well.